In the United States alone, surgeons perform approximately 600,000 by-pass operations every year to provide repair to diseased arteries and restore blood flow to the heart. While autologous saphenous veins and internal mammary arteries have typically been utilized as conduits for these operations, there are a number of complications associated with these grafts. One complication arises when the patient cannot provide autologous tissues. The symptoms of vascular disease are frequently systemic causing many of these periphery vessels to be unsuitable for vascular replacement. Even when they are usable, donor site pain and morbidity complicate the operation. Furthermore, these grafts often slowly occlude due to intimal hyperplasia necessitating subsequent surgical interventions.
Ten to twenty percent of coronary artery by-pass patients require a second operation within ten years, and frequently even patients who could provide vessels initially do not have adequate vessels for follow-up operations. Although a number of attempts have been made to develop a synthetic small-caliber vessel, the demanding, low flow environment of the vasculature typically leads to thrombosis and occlusion shortly after implantation.
Soft tissue injuries or pathological conditions are often hard to treat because replacement tissues are not available or by adding a rigid member device to the soft tissue area only creates a more dysfunctional organ. For example, damaged lung tissue is generally not repaired, but is excised by surgery. Addition of a rigid material to the lung, in an effort to repair the lung would only further comprise the lung and gas exchange functions.
What is needed are devices that are capable of providing repair for soft tissues. Ideally, these devices would be immune-compatible alternatives to autologous tissues, possess suitable properties for surgical implantation, and function in the native environment of the repaired soft tissue. Additionally, what is needed are devices that mimic soft tissue that can be used, either in vivo or in vitro, in testing agents to determine the agents effects on native soft tissue. Such devices can be used for diagnostic or therapeutic purposes, as can agents that are determined to be effective.